Gordon Brown yesterday burnished his moral credentials further when he ordered a Home Office review of legislation permitting 24-hour drinking.

The review, which is expected to report later this year on the impact on health and disorder, follows the prime minister's surprise decision not to go ahead with a super-casino in Manchester, and to consider whether cannabis should be reclassified. Mr Brown revealed the review at the first of his regular press conferences as prime minister in which he also faced questions on flooding, cash for honours, faith schools and the Middle East. His aides insisted the 24-hour drinking review would not necessarily lead to major changes.

Statistics published last week showed a small increase in violent disorder, criminal damage and harassment committed between 6pm and 6am. A study at St Thomas' hospital in London also recorded an increase in violent crime linked to the relaxed licensing laws.

It has also been argued that 24-hour drinking makes it easier for the police to handle drink-related violence as it is no longer concentrated all at one time as drinkers leave pubs.

Mr Brown said yesterday: "Clearly there are strong feelings about what has happened. There has been in increase in the number of arrests between 6pm and 6am and you might expect that, but it is not a very significant part of the amount of arrests that take place in our community."

The prime minister also acknowledged that there had been complaints about "the social effects" of 24-hour drinking.

But he added: "Let's look at the evidence when we do the review, and then let's see what the experience has been."

Mr Brown said the 24-hour laws had only been in place for two years, and there was no need "to rush to judgment". The Home Office will consult local authorities and police in areas reported to have been badly hit by the changes. Mr Brown's spokesman said last night: "He wants to examine in an objective way all the evidence. We will look at all this in the autumn with a report by the end of the year."

The prime minister also announced that he would be making a statement on security to the Commons tomorrow, in which he will set out the government's views on detention without charge for more than 28 days, and the use of phone tap evidence and of control orders. Mr Brown favours extending the limit, although his formal adviser on counter-terrorism, Lord Carlile, proposes there should be no limit, so long as there is adequate senior judicial oversight. The Home Office minister, Tony McNulty, last week said he favoured retention of the current 28-day upper limit.

Mr Brown said his statement would deal with the issue of "winning hearts and minds" and separating vulnerable young people from those who preached violence.The children's secretary, Ed Balls, is eager to understand what is happening to young Asians at an influential age, including at university. "This is a big issue and the question for us is how we can separate those extremists from the moderate, mainstream majority," Mr Brown said.

Mr Brown said he was enjoying his new job: "There's a new challenge every day." But he said the pressures of the job meant "you are not able to watch the sporting events you want to, even when you have planned to do so". So he had missed Wimbledon and the Tour de France, and expected to miss forthcoming football matches, he said.